Energy treatment instrument

1. An energy treatment instrument comprising:

an electrically conductive probe having a first electrode in a distal end portion and adapted to transmit high-frequency electric current and ultrasound vibration to the first electrode;

a sheath member adapted to cover at least part of the probe;

an electrode member having two portions, each of the two portions being provided on one of both sides of a longitudinal axis of the first electrode separately from the electrically conductive probe, each of the two portions extending substantially in parallel to the first electrode in a distal end direction to form a second electrode; and

a movable member installed at a distal end of the sheath member and configured to be openable and closable with respect to the first electrode and the second electrode, wherein

the movable member is placed at a position facing the first electrode installed at the distal end of the probe and the second electrode and includes a third electrode provided with an electrode surface configured to be able to conduct high-frequency electric current between the third electrode and the first and second electrodes,

the first electrode is provided with a planar, ultrasound processing surface and high-frequency current processing surfaces formed on both sides of the ultrasound processing surface and having two inclined surfaces,

the movable member has an insulative pad member at a position to face the ultrasound processing surface,

the third electrode is provided on both sides of the pad member,

the movable member has two surfaces that oppose the two inclined surfaces of the high-frequency current processing surfaces of the first electrode, the two surfaces corresponding to the two inclined surfaces and being separated from the two inclined surfaces by a predetermined distance when the movable jaw is in a closed state with respect to the first electrode and the second electrode, and

the second electrode is placed such that, when the movable member is brought into the closed state with respect to the first electrode and the second electrode, the first electrode and the pad member first come in contact with each other, and then an insulating member provided on the third electrode comes in contact with the second electrode, and when the insulating member and the second electrode are in contact with each other, a grasping force in a contact area between the insulating member and the second electrode is larger than a grasping force in a contact area between the first electrode and the pad member.

2. The energy treatment instrument according to claim 1 , wherein:

the second electrode is installed in a distal end portion of the sheath member; and

the sheath member includes a fitting unit used to detachably fit the sheath member over the probe.

3. The energy treatment instrument according to claim 2 , wherein when the sheath member is fitted over the probe, the fitting unit comes into contact with a member installed at a node position of ultrasound vibration performed by the probe and thereby supplies the high-frequency electric current from the probe to the second electrode.

4. The energy treatment instrument according to claim 3 , further comprising

an electrically conductive lining installed on an outer circumference of the probe, wherein

the high-frequency electric current from the probe is supplied to the second electrode via the lining.

5. The energy treatment instrument according to claim 1 , wherein

the two portions are coupled to each other at respective distal ends via a coupling unit.